2 This file is part of avahi.
4 avahi is free software; you can redistribute it and/or modify it
5 under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
9 avahi is distributed in the hope that it will be useful, but WITHOUT
10 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
11 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
12 Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with avahi; if not, write to the Free Software
16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
25 #include <sys/socket.h>
26 #include <sys/types.h>
35 #include <avahi-core/log.h>
36 #include <libdaemon/dfork.h>
40 #include "setproctitle.h"
43 AVAHI_CHROOT_SUCCESS = 0,
45 AVAHI_CHROOT_GET_RESOLV_CONF,
47 AVAHI_CHROOT_GET_SERVER_INTROSPECT,
48 AVAHI_CHROOT_GET_ENTRY_GROUP_INTROSPECT,
49 AVAHI_CHROOT_GET_ADDRESS_RESOLVER_INTROSPECT,
50 AVAHI_CHROOT_GET_DOMAIN_BROWSER_INTROSPECT,
51 AVAHI_CHROOT_GET_HOST_NAME_RESOLVER_INTROSPECT,
52 AVAHI_CHROOT_GET_SERVICE_BROWSER_INTROSPECT,
53 AVAHI_CHROOT_GET_SERVICE_RESOLVER_INTROSPECT,
54 AVAHI_CHROOT_GET_SERVICE_TYPE_BROWSER_INTROSPECT,
55 AVAHI_CHROOT_GET_RECORD_BROWSER_INTROSPECT,
57 AVAHI_CHROOT_UNLINK_PID,
58 AVAHI_CHROOT_UNLINK_SOCKET,
62 static const char* const get_file_name_table[AVAHI_CHROOT_MAX] = {
67 AVAHI_DBUS_INTROSPECTION_DIR"/org.freedesktop.Avahi.Server.xml",
68 AVAHI_DBUS_INTROSPECTION_DIR"/org.freedesktop.Avahi.EntryGroup.xml",
69 AVAHI_DBUS_INTROSPECTION_DIR"/org.freedesktop.Avahi.AddressResolver.xml",
70 AVAHI_DBUS_INTROSPECTION_DIR"/org.freedesktop.Avahi.DomainBrowser.xml",
71 AVAHI_DBUS_INTROSPECTION_DIR"/org.freedesktop.Avahi.HostNameResolver.xml",
72 AVAHI_DBUS_INTROSPECTION_DIR"/org.freedesktop.Avahi.ServiceBrowser.xml",
73 AVAHI_DBUS_INTROSPECTION_DIR"/org.freedesktop.Avahi.ServiceResolver.xml",
74 AVAHI_DBUS_INTROSPECTION_DIR"/org.freedesktop.Avahi.ServiceTypeBrowser.xml",
75 AVAHI_DBUS_INTROSPECTION_DIR"/org.freedesktop.Avahi.RecordBrowser.xml",
81 static const char *const unlink_file_name_table[AVAHI_CHROOT_MAX] = {
96 AVAHI_DAEMON_RUNTIME_DIR"/pid",
100 static int helper_fd = -1;
102 static int send_fd(int fd, int payload_fd) {
103 uint8_t dummy = AVAHI_CHROOT_SUCCESS;
108 char buf[CMSG_SPACE(sizeof(int))];
111 /* Send a file descriptor over the socket */
113 memset(&iov, 0, sizeof(iov));
114 memset(&msg, 0, sizeof(msg));
115 memset(&cmsg, 0, sizeof(cmsg));
117 iov.iov_base = &dummy;
118 iov.iov_len = sizeof(dummy);
125 msg.msg_control = &cmsg;
126 msg.msg_controllen = sizeof(cmsg);
129 cmsg.hdr.cmsg_len = CMSG_LEN(sizeof(int));
130 cmsg.hdr.cmsg_level = SOL_SOCKET;
131 cmsg.hdr.cmsg_type = SCM_RIGHTS;
132 *((int*) CMSG_DATA(&cmsg.hdr)) = payload_fd;
134 if (sendmsg(fd, &msg, 0) < 0) {
135 avahi_log_error("sendmsg() failed: %s", strerror(errno));
142 static int recv_fd(int fd) {
148 char buf[CMSG_SPACE(sizeof(int))];
151 /* Receive a file descriptor from a socket */
153 memset(&iov, 0, sizeof(iov));
154 memset(&msg, 0, sizeof(msg));
155 memset(&cmsg, 0, sizeof(cmsg));
157 iov.iov_base = &dummy;
158 iov.iov_len = sizeof(dummy);
165 msg.msg_control = cmsg.buf;
166 msg.msg_controllen = sizeof(cmsg);
169 cmsg.hdr.cmsg_len = CMSG_LEN(sizeof(int));
170 cmsg.hdr.cmsg_level = SOL_SOCKET;
171 cmsg.hdr.cmsg_type = SCM_RIGHTS;
172 *((int*) CMSG_DATA(&cmsg.hdr)) = -1;
174 if (recvmsg(fd, &msg, 0) <= 0) {
175 avahi_log_error("recvmsg() failed: %s", strerror(errno));
180 if (dummy != AVAHI_CHROOT_SUCCESS) {
185 if (!(h = CMSG_FIRSTHDR(&msg))) {
186 avahi_log_error("recvmsg() sent no fd.");
191 assert(h->cmsg_len = CMSG_LEN(sizeof(int)));
192 assert(h->cmsg_level = SOL_SOCKET);
193 assert(h->cmsg_type == SCM_RIGHTS);
195 return *((int*)CMSG_DATA(h));
199 static int helper_main(int fd) {
203 /* This is the main function of our helper process which is forked
204 * off to access files outside the chroot environment. Keep in
205 * mind that this code is security sensitive! */
207 avahi_log_debug(__FILE__": chroot() helper started");
213 if ((r = read(fd, &command, sizeof(command))) <= 0) {
219 avahi_log_error(__FILE__": read() failed: %s", strerror(errno));
223 assert(r == sizeof(command));
225 avahi_log_debug(__FILE__": chroot() helper got command %02x", command);
229 case AVAHI_CHROOT_GET_SERVER_INTROSPECT:
230 case AVAHI_CHROOT_GET_ENTRY_GROUP_INTROSPECT:
231 case AVAHI_CHROOT_GET_ADDRESS_RESOLVER_INTROSPECT:
232 case AVAHI_CHROOT_GET_DOMAIN_BROWSER_INTROSPECT:
233 case AVAHI_CHROOT_GET_HOST_NAME_RESOLVER_INTROSPECT:
234 case AVAHI_CHROOT_GET_SERVICE_BROWSER_INTROSPECT:
235 case AVAHI_CHROOT_GET_SERVICE_RESOLVER_INTROSPECT:
236 case AVAHI_CHROOT_GET_SERVICE_TYPE_BROWSER_INTROSPECT:
237 case AVAHI_CHROOT_GET_RECORD_BROWSER_INTROSPECT:
239 case AVAHI_CHROOT_GET_RESOLV_CONF: {
242 if ((payload = open(get_file_name_table[(int) command], O_RDONLY)) < 0) {
243 uint8_t c = AVAHI_CHROOT_FAILURE;
245 avahi_log_error(__FILE__": open() failed: %s", strerror(errno));
247 if (write(fd, &c, sizeof(c)) != sizeof(c)) {
248 avahi_log_error(__FILE__": write() failed: %s\n", strerror(errno));
255 if (send_fd(fd, payload) < 0)
263 case AVAHI_CHROOT_UNLINK_SOCKET:
264 case AVAHI_CHROOT_UNLINK_PID: {
265 uint8_t c = AVAHI_CHROOT_SUCCESS;
267 unlink(unlink_file_name_table[(int) command]);
269 if (write(fd, &c, sizeof(c)) != sizeof(c)) {
270 avahi_log_error(__FILE__": write() failed: %s\n", strerror(errno));
278 avahi_log_error(__FILE__": Unknown command %02x.", command);
287 avahi_log_debug(__FILE__": chroot() helper exiting with return value %i", ret);
292 int avahi_chroot_helper_start(const char *argv0) {
296 assert(helper_fd < 0);
298 if (socketpair(AF_UNIX, SOCK_STREAM, 0, sock) < 0) {
299 avahi_log_error("socketpair() failed: %s", strerror(errno));
303 if ((pid = fork()) < 0) {
306 avahi_log_error(__FILE__": fork() failed: %s", strerror(errno));
308 } else if (pid == 0) {
310 /* Drop all remaining capabilities */
311 avahi_caps_drop_all();
313 avahi_set_proc_title(argv0, "%s: chroot helper", argv0);
315 daemon_retval_done();
318 helper_main(sock[1]);
328 void avahi_chroot_helper_shutdown(void) {
337 int avahi_chroot_helper_get_fd(const char *fname) {
339 if (helper_fd >= 0) {
342 for (command = 2; command < AVAHI_CHROOT_MAX; command++)
343 if (get_file_name_table[(int) command] &&
344 strcmp(fname, get_file_name_table[(int) command]) == 0)
347 if (command >= AVAHI_CHROOT_MAX) {
348 avahi_log_error("chroot() helper accessed for invalid file name");
353 assert(get_file_name_table[(int) command]);
355 if (write(helper_fd, &command, sizeof(command)) < 0) {
356 avahi_log_error("write() failed: %s\n", strerror(errno));
360 return recv_fd(helper_fd);
363 return open(fname, O_RDONLY);
367 FILE *avahi_chroot_helper_get_file(const char *fname) {
371 if ((fd = avahi_chroot_helper_get_fd(fname)) < 0)
380 int avahi_chroot_helper_unlink(const char *fname) {
382 if (helper_fd >= 0) {
386 for (command = 2; command < AVAHI_CHROOT_MAX; command++)
387 if (unlink_file_name_table[(int) command] &&
388 strcmp(fname, unlink_file_name_table[(int) command]) == 0)
391 if (command >= AVAHI_CHROOT_MAX) {
392 avahi_log_error("chroot() helper accessed for invalid file name");
397 if (write(helper_fd, &command, sizeof(command)) < 0) {
398 avahi_log_error("write() failed: %s\n", strerror(errno));
402 if ((r = read(helper_fd, &c, sizeof(c))) < 0) {
403 avahi_log_error("read() failed: %s\n", r < 0 ? strerror(errno) : "EOF");
411 return unlink(fname);